Voltage reduction trigger discharge circuit

Abstract

The application relates to the technical field of under-voltage protection, in particular to a voltage drop triggering discharging circuit which comprises a power-off detection module, a discharging module and a power-on delay module, the power-off detection module is provided with a drop voltage value, the power-off detection module is configured to output a high-level effective power-off signal when a voltage value received by a power supply end is smaller than the drop voltage value, the discharging module is used for being connected with an external capacitive component, the discharging module discharges the external capacitive component after receiving the power-off signal output by the power-off detection module, and the power-on delay module is configured to inhibit the discharging module from receiving a sharp peak voltage signal generated by the power-off detection module at a power-on moment when a power supply is connected to the power supply end. The application has the effect of improving the power-on timing disorder of electronic products when the time interval from power-off to power-on is short.

Description

Technical Field

[0001] This application relates to the technical field of undervoltage protection, and in particular to a step-down triggered discharge circuit. Background Technology

[0002] Currently, many electronic products use capacitive components. If the power supply to an electronic product is suddenly interrupted and then quickly restored, and the time interval between the power outage and restoration is short, the energy stored in the capacitors inside the product cannot be released quickly, leaving the capacitors with a residual voltage. During the power-on phase, this residual voltage can easily cause power timing issues in the entire product.

[0003] Certain chips used in some products have strict power-on sequence requirements. Failure to strictly adhere to these sequences can lead to issues such as chip failure to boot, system crashes, program malfunctions, or even program crashes. Current technology typically involves adding resistors at points where residual internal voltage needs to be released. As long as the product is powered on, the load resistor continuously dissipates the voltage, achieving a discharge effect. However, setting the load resistor too small increases power consumption, while setting it too large results in slow residual voltage release. This fails to meet the design requirements of products with strict power-on sequences and reduces performance flexibility. This situation needs improvement. Summary of the Invention

[0004] To improve the situation where the power-on timing of electronic products is disordered when the time interval between power failure and power-on is short, this application provides a falling edge triggered discharge device with undervoltage protection.

[0005] This application provides a step-down triggered discharge circuit, which adopts the following technical solution: A step-down triggered discharge circuit includes: a power-down detection module connected to a power supply terminal, the power-down detection module having a drop voltage value, and configured to output a high-level valid power-down signal when the voltage value received at the power supply terminal is less than the drop voltage value; a discharge module connected to the power-down detection module, the discharge module being used to connect to an external capacitive component, and discharging the external capacitive component after receiving the power-down signal output by the power-down detection module; and a power-on delay module connected to the output terminal of the power-down detection module and also connected to the input terminal of the discharge module, the power-on delay module being configured to suppress the spike voltage signal generated by the power-down detection module at the moment of power-on when the power supply terminal is connected to a power source.

[0006] By adopting the above technical solution, when the product suddenly loses power, the power-down detection module detects that the voltage value received at the power supply end is less than the drop voltage value set by the power-down detection module and outputs a power-down signal. Upon receiving the power-down signal, the discharge module discharges external capacitive components. When the product suddenly powers on, the power-on delay module is activated. During the voltage rise, it will pass through the drop voltage value set point of the power-down detection module. By designing the power-on delay module, the discharge module is prevented from discharging when the voltage passes through the drop voltage value set point during the rise, thus ensuring that the discharge module does not operate during power-on. In this application's solution, the power-down detection module determines whether the product is powered off, and discharges after the product is powered off, quickly releasing the residual voltage in the product's internal components. Furthermore, by designing the power-on delay module, the discharge module does not operate after the product is suddenly powered on, thereby improving the situation where the power-on sequence of the product is disordered when the time interval between power-down and power-on is short.

[0007] Optionally, it also includes an undervoltage protection module and a main power switch module. The main power switch module is connected to the undervoltage protection module. Both the undervoltage protection module and the main power switch module are connected to the power input terminal. The undervoltage protection module has an undervoltage threshold that is lower than the drop voltage value. The undervoltage protection module is configured to output a high-level active undervoltage protection signal when the detected power supply voltage value is lower than the undervoltage threshold. The output terminal of the main power switch module is the power supply terminal. After receiving the undervoltage protection signal, the main power switch module disconnects the power input terminal and the power supply terminal.

[0008] By adopting the above technical solution, the undervoltage protection module detects and determines whether the power supply voltage is less than the undervoltage threshold. When the power supply voltage is less than the undervoltage threshold, it outputs an undervoltage protection signal. After receiving the undervoltage protection signal, the main power switch module disconnects the power input terminal and the power supply terminal. The undervoltage protection module ensures that the product is not powered when the power supply voltage does not meet the product's power supply requirements, thereby reducing unnecessary power consumption of the product.

[0009] Optionally, the power-down detection module includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first transistor, a second transistor, and a first Zener diode; the emitter of the first transistor is connected to the power supply terminal; the first resistor and the second resistor are connected in series; the first resistor is connected to the power supply terminal; the second resistor is connected to the base of the first transistor; the third resistor and the fourth resistor are connected in series; the third resistor is grounded; the fourth resistor is connected to the collector of the first transistor; the anode of the first Zener diode is grounded; the cathode of the first Zener diode is connected to the connection node between the first resistor and the second resistor; the base of the second transistor is connected to the connection node between the third resistor and the fourth resistor; the emitter of the second transistor is grounded; the fifth resistor is connected in series between the power supply terminal and the collector of the second transistor.

[0010] By adopting the above technical solution, when the product power is disconnected, the voltage value received at the power supply end is less than the drop voltage value, and a power-down signal is output to the discharge module. When the power main switch module supplies power to the product, the power-down detection module also starts to work. It detects the voltage value received at the power supply end through the first Zener diode. When the voltage value received at the power supply end is lower than the Zener diode's Zener value, the Zener diode's Zener value is equivalent to the drop voltage value set by the power-down detection module, thereby causing the discharge module to start working.

[0011] Optionally, the discharge module includes a third transistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, and a first MOSFET; the base of the third transistor is connected to the power-on delay module through the sixth resistor, the emitter of the third transistor is grounded, the collector of the third transistor is connected to the seventh resistor, the seventh resistor is connected to the power input terminal through the eighth resistor, the connection node of the seventh and eighth resistors is connected to the ninth resistor, the gate of the first MOSFET is connected to the ninth resistor, the drain of the first MOSFET is grounded through the tenth resistor, and the source of the first MOSFET is connected to an external capacitive component.

[0012] By adopting the above technical solution, the main discharge circuit is composed of the first MOSFET and the tenth resistor, and the driving circuit is composed of the third transistor, the sixth resistor, the seventh resistor, the eighth resistor and the ninth resistor to drive the operation of the main discharge circuit. When the product is powered off, when the power-down detection module detects that the voltage value received at the power supply terminal is less than the drop voltage value set by the power-down detection module, the third transistor is turned on, which pulls down the gate voltage of the first MOSFET, thereby turning on the first MOSFET to discharge the residual voltage.

[0013] Optionally, the power-on delay module includes an eleventh resistor and a first capacitor. The first capacitor is connected in parallel with the eleventh resistor. One end of the eleventh resistor is grounded, and the other end of the eleventh resistor is connected to both the output terminal of the power-off detection module and the input terminal of the discharge module.

[0014] By adopting the above technical solution, the power-on delay module consists of an RC delay circuit composed of an eleventh resistor and a first capacitor. When the main power switch module supplies power to the product, the discharge module is not triggered when the voltage rises, so that the product's working function is not activated when the power is off during normal power-on.

[0015] Optionally, the undervoltage protection module includes a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fourth transistor, and a second Zener diode; the emitter of the fourth transistor is connected to the power input terminal; the twelfth and thirteenth resistors are connected in series; the twelfth resistor is connected to the power input terminal; and the thirteenth resistor is connected to the base of the fourth transistor; the fourteenth resistor is connected in series between the collector of the fourth transistor and ground; the anode of the second Zener diode is grounded; and the cathode of the second Zener diode is connected to the connection node between the twelfth and thirteenth resistors; the collector of the fourth transistor outputs an undervoltage protection signal.

[0016] By adopting the above technical solution, the undervoltage protection module can set the undervoltage threshold through the second Zener diode. When the power supply voltage is greater than the undervoltage threshold, the second Zener diode breaks down in reverse, thereby turning on the fourth transistor. As a result, the collector of the fourth transistor outputs a high level to turn on the main power switch module.

[0017] Optionally, the power master switch module includes a second MOSFET, a fifteenth resistor, a sixteenth resistor, and a fifth transistor; the source of the second MOSFET is connected to the power input terminal, the drain of the second MOSFET is the power supply terminal, the fifteenth resistor is connected in series between the source and the gate of the second MOSFET; the collector of the fifth transistor is connected to the gate of the second MOSFET; the base of the fifth transistor is connected to the undervoltage protection module through the sixteenth resistor, and the emitter of the fifth transistor is grounded.

[0018] By adopting the above technical solution, when the input power supply voltage is less than the undervoltage threshold, the power main switch module receives the undervoltage protection signal output by the undervoltage protection module and disconnects the power input terminal and the power supply terminal.

[0019] In summary, this application includes at least one of the following beneficial technical effects: 1. In the solution of this application, the power failure detection module determines whether the product is powered off. After the product is powered off, it discharges to quickly release the residual voltage of the internal components of the product. Furthermore, by designing a power-on delay module, the discharge module does not work after the product is suddenly powered on, thereby improving the situation where the power-on sequence of the product is disordered when the time interval between power failure and power-on is short.

[0020] 2. The undervoltage protection module ensures that the product is not powered when the power supply voltage does not meet the product's power supply requirements, thereby reducing unnecessary power consumption. Attached Figure Description

[0021] Figure 1 This is a discharge principle diagram of a step-down triggered discharge circuit according to an embodiment of this application.

[0022] Figure 2 This is a schematic diagram of the undervoltage protection principle of a step-down triggered discharge circuit according to an embodiment of this application.

[0023] Figure 3 This is a schematic diagram of the working process of a step-down trigger discharge circuit according to an embodiment of this application.

[0024] Explanation of reference numerals in the attached figures: 1. Undervoltage protection module; 2. Main power switch module; 3. Power failure detection module; 4. Discharge module; 5. Power-on delay module. Detailed Implementation

[0025] The following is a further detailed description of this application.

[0026] This application discloses a step-down triggered discharge circuit. (Refer to...) Figure 1 and Figure 2It includes an undervoltage protection module 1, a main power switch module 2, a power failure detection module 3, a discharge module 4, and a power-on delay module 5. The undervoltage protection module 1 is connected to the main power switch module 2. Both the undervoltage protection module 1 and the main power switch module 2 are connected to the power input terminal. The power failure detection module 3 is connected to the power supply terminal. The discharge module 4 is connected to the power failure detection module 3. The power-on delay module 5 is connected to the output terminal of the power failure detection module 3 and is also connected to the input terminal of the discharge module 4. The undervoltage protection module 1 has an undervoltage threshold set in it. It is configured to output a high-level valid undervoltage protection signal when the detected power supply voltage is less than the undervoltage threshold. The output of the main power switch module 2 is the power supply terminal. After receiving the undervoltage protection signal, the main power switch module 2 disconnects the power input terminal and the power supply terminal. The power failure detection module 3 has a drop voltage value set in it. It is configured to output a high-level valid power failure signal when the voltage value received at the power supply terminal is less than the drop voltage value. The discharge module 4 is used to connect to external capacitive components. After receiving the power failure signal output by the power failure detection module 3, the discharge module 4 discharges the external capacitive components. The power-on delay module 5 is configured to suppress the spike voltage signal generated by the power failure detection module 3 at the moment of power-on when the power supply terminal is connected to the power supply.

[0027] In this embodiment, the drop voltage value is less than the undervoltage threshold. When the product suddenly loses power, there is a process when the input power voltage drops from the normal value to zero. When the power voltage drops below the drop voltage value but above the undervoltage threshold, the power failure detection module 3 detects that the voltage value received at the power supply terminal is less than the drop voltage value set by the power failure detection module 3 and outputs a power failure signal. After receiving the power failure signal, the discharge module 4 discharges the external capacitive components. The input power voltage continues to decrease until it drops below the undervoltage threshold. At this point, the undervoltage protection module 1 detects that the power voltage value is less than the undervoltage threshold and outputs an undervoltage protection signal. After receiving the undervoltage protection signal, the power main switch module 2 disconnects the power input terminal and the power supply terminal, so that the product will not be powered on when the power voltage is too low, improving the safety of product use. Furthermore, during the stage from the drop voltage value to the undervoltage threshold, it can be ensured that the discharge module 4 has sufficient discharge time for the externally connected capacitive components.

[0028] When the product is suddenly powered on, the undervoltage protection module 1 activates first during the voltage rise process, thus enabling power conduction. At the instant of power conduction, the power-on delay module 5 activates to absorb the voltage spike at the moment of power-on. During the voltage rise phase and after passing the drop voltage set point of the power-off detection module 3, the power-on delay module 5 is designed to prevent the discharge module 4 from discharging, thus ensuring that the discharge module 4 does not operate during power-on. In this application's solution, the power-off detection module 3 determines whether the product is powered off, and discharges after the product is powered off, quickly releasing the residual voltage in the product's internal components. Furthermore, by designing the power-on delay module 5, the discharge module 4 is prevented from operating after the product is suddenly powered on, thereby improving the situation where the power-on sequence of the product is disordered when the time interval between power-off and power-on is short.

[0029] Reference Figure 1 The undervoltage protection module 1 includes a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fourth transistor B4, and a second Zener diode D2. The emitter of the fourth transistor B4 is connected to the power input terminal. The twelfth resistor R12 and the thirteenth resistor R13 are connected in series. The twelfth resistor R12 is connected to the power input terminal, and the thirteenth resistor R13 is connected to the base of the fourth transistor B4. The fourteenth resistor R14 is connected in series between the collector of the fourth transistor B4 and the ground. The anode of the second Zener diode D2 is grounded, and the cathode of the second Zener diode D2 is connected to the connection node between the twelfth resistor R12 and the thirteenth resistor R13. The collector of the fourth transistor B4 outputs an undervoltage protection signal.

[0030] In this embodiment, the undervoltage protection module 1 can set an undervoltage threshold through the second Zener diode D2. When the power supply voltage is greater than the undervoltage threshold, the second Zener diode D2 breaks down in reverse, thereby turning on the fourth transistor B4. After the fourth transistor B4 turns on, its collector is at a high level, thus outputting a high level, thereby controlling the power main switch module 2 to turn on. The undervoltage threshold is the voltage between the twelfth resistor R12 and ground at the instant the second Zener diode D2 breaks down in reverse.

[0031] Reference Figure 1 The main power switch module 2 includes a second MOSFET Q2, a fifteenth resistor R15, a sixteenth resistor R16, and a fifth transistor B5. The source of the second MOSFET Q2 is connected to the power input terminal, and the drain of the second MOSFET Q2 is connected to the power supply terminal via the power-down detection module 3. The fifteenth resistor R15 is connected in series between the source and gate of the second MOSFET Q2. The collector of the fifth transistor B5 is connected to the gate of the second MOSFET Q2. The base of the fifth transistor B5 is connected to the undervoltage protection module 1 via the sixteenth resistor R16, and the emitter of the fifth transistor B5 is grounded.

[0032] In this embodiment, when the power supply voltage reaches the product's rated voltage, i.e., when the power supply voltage exceeds the undervoltage threshold, the main power switch module 2 supplies power to the product. At this time, the fourth transistor B4 of the undervoltage protection module 1 is turned on, and the collector of the fourth transistor B4 is at a high level. At this time, the fifth transistor B5 is turned on. Since the fifth transistor B5 is turned on, the gate of the second MOSFET Q2 is at a low level, and the second MOSFET Q2 is turned on, thus turning on the main power switch module 2 and realizing the connection between the power input terminal and the power supply terminal.

[0033] Reference Figure 2 The power-down detection module 3 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first transistor B1, a second transistor B2, and a first Zener diode D1. The emitter of the first transistor B1 is connected to the power supply terminal. The first resistor R1 and the second resistor R2 are connected in series. The first resistor R1 is connected to the power supply terminal, and the second resistor R2 is connected to the base of the first transistor B1. The third resistor R3 and the fourth resistor R4 are connected in series. The third resistor R3 is grounded, and the fourth resistor R4 is connected to the collector of the first transistor B1. The anode of the first Zener diode D1 is grounded, and the cathode of the first Zener diode D1 is connected to the connection node between the first resistor R1 and the second resistor R2. The base of the second transistor B2 is connected to the connection node between the third resistor R3 and the fourth resistor R4, and the emitter of the second transistor B2 is grounded. The fifth resistor R5 is connected in series between the power supply terminal and the collector of the second transistor B2.

[0034] In this embodiment, the dropout voltage is the voltage between the first resistor R1 and ground at the instant the first Zener diode D1 undergoes reverse breakdown. When the voltage received at the power supply terminal is lower than the dropout voltage, the first transistor B1 is cut off, and its collector is at a low level. Since the first transistor B1 is at a low level, the second transistor B2 is cut off, and therefore at a high level. This high-level discharge signal controls the discharge module 4 to discharge the externally connected capacitive components.

[0035] When the voltage received at the power supply end is greater than the drop voltage, the first transistor B1 is turned on. At this time, the collector of the first transistor B1 is at a high level. Since the first transistor B1 is at a high level, the second transistor B2 is turned on. Therefore, the second transistor B2 is at a low level and cannot trigger the discharge module 4 to start.

[0036] Reference Figure 2The discharge module 4 includes a third transistor B3, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, and a first MOSFET Q1. The base of the third transistor B3 is connected to the power-on delay module 5 through the sixth resistor R6. The emitter of the third transistor B3 is grounded. The collector of the third transistor B3 is connected to the seventh resistor R7. The seventh resistor R7 is connected to the power input terminal through the eighth resistor R8. The connection node of the seventh resistor R7 and the eighth resistor R8 is connected to the ninth resistor R9. The gate of the first MOSFET Q1 is connected to the ninth resistor R9. The drain of the first MOSFET Q1 is grounded through the tenth resistor R10. The source of the first MOSFET Q1 is connected to an external capacitive component.

[0037] In this embodiment, the main discharge circuit is composed of the first MOSFET Q1 and the tenth resistor R10, and the driving circuit is composed of the third transistor B3, the sixth resistor R6, the seventh resistor R7, the eighth resistor R8 and the ninth resistor R9 to drive the main discharge circuit. When the product is powered off, when the power-down detection module 3 detects that the voltage received at the power supply terminal is less than the drop voltage value set by the power-down detection module 3, the third transistor B3 is turned on, which pulls down the gate voltage of the first MOSFET Q1, thereby turning on the first MOSFET Q1 to discharge the connected external capacitive components.

[0038] Reference Figure 2 The power-on delay module 5 includes an eleventh resistor R11 and an eleventh resistor C1. The eleventh resistor C1 is connected in parallel with the eleventh resistor R11. One end of the eleventh resistor R11 is grounded, and the other end of the eleventh resistor R11 is connected to both the output terminal of the power-off detection module 3 and the input terminal of the discharge module 4.

[0039] In this embodiment, after the power switch module 2 supplies power to the product, the first transistor B1 needs a certain amount of time to turn on, so the second transistor B2 will be briefly cut off. This causes the discharge module 4 to discharge briefly at the moment of power-on. Therefore, the power-on delay module 5 is used to avoid this. The power-on delay module 5 consists of an eleventh resistor R11 and a first capacitor C1 forming an RC delay circuit. When the power switch module 2 supplies power to the product, it ensures that the discharge module 4 is not triggered when the voltage rises, so that the product's working function is not activated when the power is off during normal power-on.

[0040] In this embodiment, when the product suddenly loses power, if the voltage received at the power supply terminal is less than the drop voltage, the third transistor B3 conducts, causing the gate voltage of the first MOSFET Q1 to drop, thereby turning on the first MOSFET Q1 and discharging the connected external capacitive components. If the power supply voltage is suddenly restored after the product loses power, and the power supply voltage is less than the undervoltage threshold, the main power switch module 2 cannot be turned on, and the product is not powered. If the power supply voltage is greater than the undervoltage threshold, the second Zener diode D2 breaks down in reverse, causing the fourth transistor B4 to conduct. After the fourth transistor B4 conducts, its collector is at a high level, resulting in a high-level output from the collector of the fourth transistor B4, which controls the main power switch module 2 to conduct, and the product receives power. After the main power switch module 2 supplies power to the product, the power supply voltage is greater than the undervoltage threshold. During the voltage rise phase and after passing the drop voltage setting point of the power failure detection module 3, the first transistor B1 needs a certain amount of time to conduct, so the second transistor B2 will be briefly cut off. This causes the discharge module 4 to discharge briefly at the moment of power-on. Therefore, the power-on delay module 5 is used to avoid this, so that the discharge module 4 is not triggered when the voltage rises, so that the product's working function is not activated when the power is off during normal power-on.

[0041] A step-down trigger discharge circuit can be designed using discrete components. The circuit is simple and flexible. By modifying the parameters of the second Zener diode D2 and the first Zener diode D1, the circuit can be adapted to different power inputs. Moreover, the circuit discharges only on the falling edge, so that the discharge module 4 is not triggered when the voltage is on the rising edge.

[0042] For example Figure 3 Taking the example diagram shown, after power is input to the product, it first determines whether the undervoltage protection module 1 is triggered. If triggered, an undervoltage protection signal is output, and the main power switch module 2 remains closed after receiving the undervoltage protection signal. If the undervoltage protection module 1 is not triggered, the main power switch module 2 is turned on to power the product. At the same time, the power-on delay module 5 is used to avoid triggering the discharge module 4 when the voltage rises, so that the product's working function does not start when the power is off when it is normally powered on. Then, it determines whether the power failure detection module 2 is triggered. If the power failure detection module 2 is triggered, a power failure signal is output. After receiving the power failure signal, the discharge module 4 discharges the connected external capacitive components. If the power failure detection module 2 is not triggered, the discharge module 4 remains closed.

[0043] The implementation principle of a voltage-triggered discharge circuit in this application embodiment is as follows: When the product suddenly loses power, the power-down detection module 3 detects that the voltage value received at the power supply end is less than the drop voltage value set by the power-down detection module 3 and outputs a power-down signal. After receiving the power-down signal, the discharge module 4 discharges the external capacitive components. When the product suddenly powers on, the power-on delay module 5 starts. During the voltage rise, it will pass through the drop voltage value set point of the power-down detection module 3. By designing the power-on delay module 5, when the voltage passes through the drop voltage value set point during the rise, the discharge module 4 will not be triggered to discharge, thus achieving that the discharge module 4 does not work when powered on. When the product needs to be powered on again, the undervoltage protection module 1 detects and judges whether the power supply voltage value is less than the undervoltage threshold. When the power supply voltage value is less than the undervoltage threshold, it outputs an undervoltage protection signal. After receiving the undervoltage protection signal, the power main switch module 2 disconnects the power input end and the power supply end. The undervoltage protection module 1 ensures that the product is not powered when the power supply voltage value does not meet the product's power supply requirements, thereby reducing unnecessary power consumption of the product. In the solution of this application, the power failure detection module 3 determines whether the product is powered off. After the product is powered off, it discharges to quickly release the residual voltage of the internal components of the product. Furthermore, by designing the power-on delay module 5, the discharge module 4 is not activated after the product is suddenly powered on, thereby improving the situation where the power-on sequence of the product is disordered when the time interval between power failure and power-on is short.

[0044] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A step-down trigger discharge circuit, characterized in that, include: The main power switch module (2) is connected to the power input terminal, and the output terminal of the main power switch module (2) is the power supply terminal; Power failure detection module (3), the power failure detection module (3) is connected to the power supply terminal, the power failure detection module (3) is set with a drop voltage value, and the power failure detection module (3) is configured to output a high-level active power failure signal when the voltage value received at the power supply terminal is less than the drop voltage value; The discharge module (4) is connected to the power-down detection module (3). The discharge module (4) is used to connect with external capacitive components. After receiving the power-down signal output by the power-down detection module (3), the discharge module (4) discharges the external capacitive components. Power-on delay module (5), the power-on delay module (5) is connected to the output terminal of the power-off detection module (3) and also connected to the input terminal of the discharge module (4). The power-on delay module (5) is configured to suppress the transmission of the spike voltage signal generated by the power-off detection module (3) at the moment of power-on to the discharge module (4) when the power supply terminal is connected to the power supply. The power-down detection module (3) includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first transistor, a second transistor, and a first Zener diode; the emitter of the first transistor is connected to the power supply terminal, the first end of the first resistor is connected to the power supply terminal, the second end of the first resistor is connected to the first end of the second resistor, and the second end of the second resistor is connected to the base of the first transistor; the first end of the third resistor is connected to the first end of the fourth resistor, the second end of the third resistor is grounded, and the second end of the fourth resistor is connected to the collector of the first transistor; the anode of the first Zener diode is grounded, and the cathode of the first Zener diode is connected to the connection node between the first resistor and the second resistor; the base of the second transistor is connected to the connection node between the third resistor and the fourth resistor, and the emitter of the second transistor is grounded; the first end of the fifth resistor is connected to the power supply terminal, and the second end of the fifth resistor is connected to the collector of the second transistor; The power-on delay module (5) includes an eleventh resistor and a first capacitor. The first capacitor is connected in parallel with the eleventh resistor. One end of the eleventh resistor is grounded, and the other end of the eleventh resistor is connected to both the output terminal of the power-off detection module (3) and the input terminal of the discharge module (4).

2. The step-down trigger discharge circuit according to claim 1, characterized in that, It also includes an undervoltage protection module (1), the power main switch module (2) is connected to the undervoltage protection module (1), the undervoltage protection module (1) is connected to the power input terminal, the undervoltage protection module (1) is set with an undervoltage threshold, the undervoltage threshold is lower than the drop voltage value, the undervoltage protection module (1) is configured to output an undervoltage protection signal when the detected power supply voltage value is less than the undervoltage threshold; after receiving the undervoltage protection signal, the power main switch module (2) disconnects the power input terminal and the power supply terminal.

3. The step-down trigger discharge circuit according to claim 1, characterized in that, The discharge module (4) includes a third transistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, and a first MOSFET. The base of the third transistor is connected to the power-on delay module (5) through the sixth resistor. The emitter of the third transistor is grounded. The collector of the third transistor is connected to the first end of the seventh resistor. The second end of the seventh resistor is connected to the power input terminal through the eighth resistor. The connection node of the seventh resistor and the eighth resistor is connected to the first end of the ninth resistor. The gate of the first MOSFET is connected to the second end of the ninth resistor. The drain of the first MOSFET is grounded through the tenth resistor. The source of the first MOSFET is connected to an external capacitive component.

4. The step-down trigger discharge circuit according to claim 2, characterized in that, The undervoltage protection module (1) includes a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fourth transistor, and a second Zener diode. The emitter of the fourth transistor is connected to the power input terminal. The first end of the twelfth resistor is connected to the first end of the thirteenth resistor, the second end of the twelfth resistor is connected to the power input terminal, and the second end of the thirteenth resistor is connected to the base of the fourth transistor. The first end of the fourteenth resistor is grounded, and the second end of the fourteenth resistor is connected to the collector of the fourth transistor. The anode of the second Zener diode is grounded, and the cathode of the second Zener diode is connected to the connection node between the twelfth and thirteenth resistors. The collector of the fourth transistor outputs an undervoltage protection signal.

5. The step-down trigger discharge circuit according to claim 2, characterized in that, The power switch module (2) includes a second MOSFET, a fifteenth resistor, a sixteenth resistor, and a fifth transistor; the source of the second MOSFET is connected to the power input terminal, the drain of the second MOSFET is the power supply terminal, the first end of the fifteenth resistor is connected to the source of the second MOSFET, and the second end of the fifteenth resistor is connected to the gate of the second MOSFET; the collector of the fifth transistor is connected to the gate of the second MOSFET; the base of the fifth transistor is connected to the undervoltage protection module (1) through the sixteenth resistor, and the emitter of the fifth transistor is grounded.

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